Heat exchangers such as vehicular radiators include cores which are defined by a plurality tube and interleaved fins which terminate at opposed ends in header plates. To provide a means of directing liquid to the interior of the tubes, a so-called tank is secured to each header plate and some sort of means provided to introduce liquid into the tank.
This, of course, means that the tank must be properly sealed to the header plate or else a leaky system will result. Consequently, much effort has been expended in providing various means whereby tanks may be secured to header plates.
Frequently, relatively permanent connections have been attempted. This is undesirable from the standpoint that when the core becomes unusable, the entire heat exchanger including the tanks is disposed of and the replacement cost is more expensive. Consequently, from this standpoint, it is desirable to provide a readily severable but tightly sealed header to tank joint.
Another consideration arises when the header plates and the tank are of dissimilar materials. State of the art vehicular radiator design calls for the tanks to be made of plastic whereas the cores are copper-brass or aluminum in most cases. Plastic tanks reduce the overall weight of the heat exchanger, and thus the vehicle and contribute to fuel efficiency.
In establishing a sealed connection between a tank and a header plate made of dissimilar materials, some care must be exercised to assure that the softer of the two materials is not damaged in the joining operation.
In order to meet these and other needs, Keyzer in U.S. Pat. No. 4,645,002 issued Feb. 24, 1987, has proposed a removable, tank retaining strip for securing the heat exchanger tank to a header plate. The Keyzer construction is shown in FIGS. 1 and 2 hereof and is seen to include a tank 10 having a peripheral, outwardly extending flange 11 applied to a header plate 14. Extending through the header plate 14 is a plurality of open tube ends 16 of flattened tubes 18 which extend in generally parallel relation to each other to another header plate (not shown) and between which serpentine fins 20 extend in a conventional fashion. The body of the header plate 14 is surrounded by a peripheral groove 22. The groove 22 includes an inner wall 24 an upstanding outer wall or flange 26 and a bottom 28 defining a seal receiving surface. Located within the groove 22 is a resilient seal 30 which is compressed against the sealing surface 28 at the bottom of the groove 22 by abutment with the sealing surface 32 on the underside of the peripheral flange 11 of the tank 10.
By compressing the seal 30, a peripheral seal at the tank to header plate joint is maintained. In order to compress the seal, the tank 10, and specifically, the peripheral flange 11, includes an upper, pressure receiving surface 34 that is opposite the sealing surface 32.
Located about the upstanding flange 26 is a row of apertures made up of elongated slots 36. An elongated retaining strip 38 extends along the upstanding flange 26 as can be best seen in FIG. 1 and includes a plurality of inwardly directed fingers 40 that extend into corresponding ones of the slots 36 to overlie and abut the surface 34 of the flange 11. As a consequence, the flange 11 can be held in compressing relation against the seal 30.
To prevent dissociation of the strip 38, Keyzer provides deformations or dimples 42 in each finger 40 which extend upwardly. Because the resilience of the seal 30 will exert an upward bias against the flange 11 which in turn will be applied to each of the fingers 40, the dimples 42 may lodge behind the innermost surface 44 of the upstanding flange 26 to provide a locking action.
As a consequence of this construction, a good peripheral seal may be maintained if assembly is properly accomplished. Furthermore, disassembly of a tank from a core is readily accomplished simply by exerting a force against the tank 10 to further compress the seal 30, allowing the strip 38 to be pulled away from the flange 26.
However, if the Keyzer strip is not properly installed, or if the heat exchanger employing the same is handled improperly, the retention provided by the strip may be lost. For example, because the strip is typically formed of relatively thin metal, it is subject to some flexure, being what might be termed only "semi-rigid". As a consequence, while certain of the fingers 40 may be fully located within their associated slots 36 and the dimples 42 properly oriented as shown in FIG. 2, it is possible that certain others of the fingers along the length of the upstanding flange 26 are not fully disposed within their associated slots 36 so as to allow the dimples 42 to accomplish their retaining purpose. When this occurs, cycling of the heat exchange during its operation may result in ultimate loosening of the strip and the formation of a leak at that location.
Similarly, if the assembled heat exchanger is mishandled, as by dropping the heat exchanger on one of the tanks, a sudden over-compression of the seal 30 may result, allowing the strip 38 and the fingers 40 to move and dissociate themselves. Again, leakage will occur.
The present invention is directed to overcoming one or more of the above problems.